This invention relates to a method for separating rare earth metals at high efficiency. More particularly, it relates to a method for separating and recovering rare earth metals at a high elution rate and high efficiency by using an ion exchange fiber.
Rare earth metals such as lanthanum, yttrium, cerium, neodymium, samarium and the like are widely used as a component of ceramic material, hydrogen absorbent, alloy component, catalyst component, or the like. Usually these metals occur in a mingled state, so that they have to be separated into a pure component. However, since the rare earth metals are closely akin to each other in properties, their separation is attended by great difficulties, and only a few metals such as cerium and europium can be finely separated by conventional separation means such as fractional crystallization and fractional precipitation.
A method using an ion exchange resin has been proposed (Journal of Chromatography, 66, 129-135 (1972); 76, 213-220 (1973), but this method is yet unsatisfactory for practical application because it is of a batch type and requires as long a time as several tens of days for one run of separating operation and the apparatus is enlarged to cause reduction in productivity. Solvent extraction is a technique which is most commonly used as an established method for the metal separation, but this method is also not always satisfactory as an industrial process because of complicacy of the operation and the problem in disposal of the used solvent. Thus, the development of a method which enables separation of rare earth metals in a high purity by a simple, non-time-consuming operation has been a matter of primary concern in the industrial fields using rare earth metals.